The project seeks to understand the clinical and molecular basis of syndromic microphthalmia. This disorder comprises anophthalmia or microphthalmia (small or absent eyes with blindness), mental retardation, and skeletal anomalies. We have identified a large family affected by Lenz Microphthalmia and have mapped the gene to the short arm of the X chromosome. This result is surprising because another family with this disorder maps to the long arm of the X chromosome. This means that Lenz microphthalmia is probably an amalgam of two disorders. We have used positional cloning to isolate the gene that is altered in the condition, which is called BCOR (BCL-6 co-repressor). In addition, we have discovered that mutations in this gene also cause the Oculo-facio-cardi-dental syndrome. We are currently assessing the functional consequence of these mutations in a zebrafish model system.